Ly located on endothelial surfaces of larger vessels on small arteries and arterioles [111, 112]. APC is also known for its anti-inflammatory properties [113-116]. The PC system is physiologically very important, as is most clearly demonstrated by the severe thromboembolic disease associated with homozygous deficiency of PC [108, 117-119] or protein S [120]. Finally, heparin cofactor II is a prote